How Radon Mitigation Systems Work

When a Kansas City test comes back above the action level, the word mitigation sounds like a big project. It is usually not. A standard system is a length of pipe and a quiet fan, and once it is running you mostly forget it is there. Here is what it actually does and why it works so well on our local homes.

The idea behind it

Radon comes up out of the ground as uranium in the soil breaks down. Your heated house acts like a chimney, so it gently pulls that soil gas up through cracks in the slab, the sump pit, and gaps around plumbing. A mitigation system beats the house at its own game. Instead of letting the gas seep up into your living space, it grabs it under the slab and sends it up and out above the roof, where it scatters harmlessly. The trade name for the common version is sub-slab depressurization, which is a mouthful for a simple thing.

The parts of a system

A typical Kansas City install is short list of parts. There is a suction point cut into the basement slab or crawl space, a run of PVC pipe carrying the gas up through the house or along an outside wall, an inline fan that runs continuously and pulls the gas along, and a small manometer gauge you can glance at to confirm the fan is working. That is really it. No chemicals, no filters to swap, nothing you have to operate.

Why it works under KC homes

Most homes in the metro sit on a slab or a crawl space over that heavy clay soil, and that setup is ideal for sub-slab suction. The fan creates a slight vacuum in the gravel or soil under the floor, so instead of drifting up into the basement, the radon follows the path of least resistance into the pipe. A crawl space gets a sealed membrane first so the fan has something to pull against. Done right, a system brings almost any home well under the 4 pCi/L action level, and a good installer retests to prove it.

Living with the system

The fan uses about as much power as a light bulb and runs quietly outside or in the attic. Fans last years but not forever, so at some point one needs replacing, which is a quick job. Checking the manometer once in a while is the only upkeep. If you ever finish a basement or add a sump later, it is worth a quick look to make sure the system still covers the space.

If you have a number in hand and are weighing what comes next, that is the right time to talk to a local installer who has worked on homes like yours.

Frequently asked questions